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  • Author or Editor: C. Yonezawa x
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Abstract  

A neutron-induced prompt -ray analysis (PGA) has become widely utilized due to the improved analytical sensitivities and detection limits especially by using low energy guided neutron beams. Current studies on the low energy neutron guided beam PGA are reviewed. Historical backgrounds, current analysis systems, advantages when compared with conventional NAA, standardization for elemental determination and analytical applications in JAERI of the guided beam PGA are described.

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Abstract  

The extraction of UO 2 2+ , Am3+, and Th4+ by 1-phenyl-3-methyl-4-benzylpyrazolone with crown ethers was studies using 0.1M (NaClO4) aqueous phase and toluene. The crown ethers were 12C4, 15C5, 18C6, DB18C6 and DCH18C6. The synergic equilibrium constant did not show correlation between the cationic radii and the ether cavity size nor did the values follow a simple order of ether basicity. The ether basicity, steric effects, and the number of ether oxygens bound to the cation are the combined factors which seemingly determine the pattern of M(PMBP)n—CE interaction.

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Abstract  

Non-destructive multi-element determination in environmental samples by neutron-induced prompt -ray analysis (PGA) has been investigated. Comparative standardization for the elements including H, B, C, N, Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Mn, Fe, Co, Cd, Sm, Gd, Hg by PGA has been carried out using the cold and thermal guided neutron beams of JRR-3M reactor and then several environmental reference materials have been analyzed. Accuracy and precision of better than 20% were found for these elemental analyses except for H, C, N and Cl in biological samples. Detection limits in various environmental matrices were 25 to 820 ng/g for B, Cd, Sm and Gd, 1.1 to 820 g/g for H, Na, S, Cl, K, Ti, Mn, Co and Hg, and 0.031 to 10% for C, N, Mg, Al, Si, P, Ca and Fe. The present method is being applied to environmental studies of post war Persian Gulf together with INAA and ICP-MS.

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Abstract  

Multi-element and isotopic analyses of oils and marine environmental samples were carried out to estimate a contamination source using a "finger printing" method. Elemental analyses were carried out using neutron-induced prompt gamma-ray analysis (PGA), instrumental neutron activation analysis (INAA) at the Japan Atomic Energy Research Institute, Tokai-mura, Japan (JAERI) and ICP-MS in the IAEA Marine Environment Laboratory, Monaco (MEL). Fifteen elements including light elements, H, B, N, Si and Ca, which cannot be determined by INAA and ICP-MS, were determined by PGA. A total of 47 elements were determined in the present study. The potential of PGA for the determination of isotopic ratios was tested by measuring 34S/32S ratios in oils. The evaluation of historical records of marine environmental conditions using annual bands in coral samples was also investigated.

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Abstract  

For the determination of specific activity of63Ni, a method has been developed for simultaneous assessment of both stable and radionickel. The method comprises solvent extraction of Ni-dimethylglyoxime into xylene for spectroscopic measurement and liquid scintillation counting of the extractant. The application of the method has been successful for63Ni in the corrosion products accumulated on the wall surface in the primary circuiting tube of the reactor.

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Abstract  

Determination of ppm levels of B in 21 igneous and sedimentary rocks of the Japanese geochemical reference samples prepared by the Geological Survey of Japan (GSJ) has been performed by neutron-induced prompt γ-ray analysis (PGA) using cold and thermal guided neutron beams of the JRR-3M. Owing to the Doppler broadened γ-ray line of B 478 keV, many elements such as Na, Ni, Cl and so on showed spectral interference in the determination of B. The interference was corrected by computer fitting and a reference peak method. The analytical results obtained by the present method almost agreed with the GSJ values recommended in 1994 within the standard deviation of the recommended values. Sodium contents determined by the PGA in the reference rock samples are also reported.

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Abstract  

A method is proposed for the implementation of large-sample prompt-gamma neutron activation analysis (LS-PGNAA). The method was tested with four different sample materials at the thermal PGNAA facility at JAERI, Japan. The macroscopic scattering cross section (Σ s) and absorption cross section (Σ a) of the samples were determined by monitoring the neutron flux in four positions just outside the sample container. With the Σ s and Σ a determined, the spatial neutron density distribution [n(r)] inside the sample material was derived. Taking n(r) and the gamma-ray self-absorption into account simultaneously, the effective geometric gamma-ray detection efficiency for large samples as a function of gamma-ray energy was calculated. Taking silicon as test element, the concentrations found agreed to within 7% with the known concentrations in the four sample materials examined, both when using relative standardization and with absolute standardization.

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Summary  

By probing Doppler broadened line-shapes of prompt γ -ray at 478 keV emitted from moving 7*Li produced via the 10B(n, γ)7*Li reaction, matrix materials containing and/or surrounding boron species were non-destructively characterized for several growing stages of soybean. It was elucidated that boron is in the form close to each other for both the dry seeds for planting and the dry seeds harvested, while it was revealed that boron exists in an aqueous solution for the two stages of growing, swelling seeds with a bourgeon and a greenish sprout. This work is the first biological application of Doppler broadening of neutron induced prompt γ -rays.

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Abstract  

The application of stable isotope analysis using neutron-induced prompt -ray analysis (PGA) with cold/thermal neutron beams for the tracer study of geological materials are discussed. Silicon has three natural isotopes differing in abundance:28Si (92.23%),29Si (4.67%) and30Si (3.10%). For the purpose of the assessment of Si migration in engineered barrier material, enriched30Si can be used as a tracer due to its nuclear and chemical properties. Isotope analysis of30Si was performed by PGA during the tracer study. Neutron intensity at the sample position was 1.4·108 n¢cm–2·s–1, 2.4·107 n·cm–2·s–1 for cold and themal neutron guided beams of JRR-3M, respectively. Calibration curves and analytical sensitivity of30Si were determined based on measurement of standard samples. BG and detection limits for30Si analysis were also measured in Japanese bentonite (Kunigel V1 and Kunipia F) and their pore water. Fiffteen elements were determined simultaneously using PGA.

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Abstract  

The spectral lines of the 478 keV prompt -ray from7*Li produced in the10B(n, )7*Li reaction were measured for a silicon wafer coated with a thin boron layer using neutron beams. The shapes of the Doppler broadened lines were found to depend greatly on the angle between the measurement axis and the boron layer surface. The angular dependence was interpreted according to whether the energetic7*Li ions are ejected into air or into the substance in the forward or backward recoil of7*Li to the -ray detector.

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